title: Adhesive cementation of zirconia posts to root dentin: evaluation of the mechanical cycling effect.
abstract: This study evaluated the effect of mechanical cycling on the bond strength of zirconia posts to root dentin. Thirty single-rooted human teeth were transversally sectioned to a length of 16 mm. The canal preparation was performed with zirconia post system drills (CosmoPost, Ivoclar) to a depth of 12 mm. For post cementation, the canals were treated with total-etch, 3-steps All-Bond 2 (Bisco), and the posts were cemented with Duolink dual resin cement (Bisco). Three groups were formed (n = 10): G1 - control, no mechanical cycling; G2 - 20,000 mechanical cycles; G3 - 2,000,000 mechanical cycles. A 1.6-mm-thick punch induced loads of 50 N, at a 45 degrees angle to the long axis of the specimens and at a frequency of 8 Hz directly on the posts. To evaluate the bond strengths, the specimens were sectioned perpendicular to the long axis of the teeth, generating 2-mm-thick slices, approximately (5 sections per teeth), which were subjected to the push-out test in a universal testing machine at a 1 mm/min crosshead speed. The push-out bond strength was affected by the mechanical cycling (1-way ANOVA, p = .0001). The results of the control group (7.7 +/- 1.3 MPa) were statistically higher than those of G2 (3.9 +/- 2.2 MPa) and G3 (3.3 +/- 2.3 MPa). It was concluded that the mechanical cycling damaged the bond strength of zirconia posts to root dentin.
authors.affiliation: Dept. of Dental Materials and Prosthodontics, School of Dentistry of São José dos Campos, São Paulo State University, São José dos Campos, SP, Brazil. grazielagalhano@yahoo.com.br
authors.forename: Graziela Avila
authors.initials: GA
authors.lastname: Galhano
authors.forename: Renata Marques de
authors.initials: RM
authors.lastname: Melo
authors.forename: Carlos Augusto
authors.initials: CA
authors.lastname: Pavanelli
authors.forename: Paolo
authors.initials: P
authors.lastname: Baldissara
authors.forename: Roberto
authors.initials: R
authors.lastname: Scotti
authors.forename: Luiz Felipe
authors.initials: LF
authors.lastname: Valandro
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Bottino
mesh_terms: D000704:Analysis of Variance; D002516:Ceramics / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods*; D003799:Dental Stress Analysis / Q000379:methods; D003804:Dentin / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D011176:Post and Core Technique / Q000295:instrumentation* / Q000592:standards; D019279:Resin Cements / Q000737:chemistry*; D018915:Root Canal Preparation; D013314:Stress, Mechanical; D013718:Tensile Strength; D015040:Zirconium / Q000737:chemistry*
chemical_list: D019279:Resin Cements; D015040:Zirconium; C028541:zirconium oxide